Change air filter for a free flow one-either an induction kit or one that fits in your existing airbox(just a replacement that allows air to be sucked in quicker)

Change exhaust-again for better flow of exhaust gases the quicker ya can get air in and gases out the more responsive it will "seem" though may only really be noticed at high revs.

Dont know the setup of the exhaust on a non turbo so cant give advise on actual products sorry.

Other than that i`d lower and uprate suspension-if ya make it a more capable car you`d be suprised on how that has an effect on how confident you`ll be to push it further-couple that with some decent tyres/brake pads an you`ll be able to make the best of what youve got without breaking the bank.

Decent Tyres For 17`s (just an example not sure of your wheel size)£320 for 4.

Decent pads Anywhere i guess from £60-£100 (per set of 4 pads)

Green panel filter for std airbox around £40ish

Its easy to agree with ya tidgy a non turbo car of any manufacturer doesnt respond to mods like any of the turbo cars (regarding engine mods) however ive got a few mates with hot hatches that`d suprise ya an none of em`s turbo`d/supercharged.

You get a driver that can get the full potential out of any car by getting the handling right hence inspiring confidence/ability an i tell ya what ya`d be amazed.

Not saying for one minute Pauls gonna be pushing sti`s around but you`ll be suprised the difference money in the right places makes to a car and the driver.

this car don't need 3" exhaust system. enough to remove the cat. get free flow air filter, buy the Wide Band lambda and get air/fuel mix tuned.
probably you can get chip for this car but it more expensive.

the short version is a chiped sport wont keep up with a standard turbo, unless your talking back roads with a shit hot driver in it or the turbo'd car is playing up. the difference is the best part of 70bhp power at least, which is 40% ish power difference.

there are plenty of things you can do to it, cams, throttle body's etc etc, however the cost of doing this is extream compared to the perforamcne gains. you can get a none turbo up to 200bhp+ but your talking some serious engine building and setup which is prob gonna be 5-10k (unless you do it yourself of course). for that money you can buy a turbo'd car and drop 5k into it and prob be getting close to 350bhp.

running a supercharger is pretty much the same as running a turbo. but then it drops back to other components which are uprated on the turbo'd car compared to the sport.

All in all its cheaper to sell the car and buy a turbo'd car, changing the exhaust will give you a nice sound, doing the suspension, if you pick the right ones, will be transferable between the sport and turbo so you improve the handeling.